1. Field of the Invention
The invention relates to cleaning heads for use in the bottoms of swimming pools, and more particularly, to cleaning heads which eject jets of water in successive angular directions about a center point along the bottom of a swimming pool as water pressure applied to the cleaning head is intermittently cycled on and off.
2. Description of the Prior Art
A variety of automatic pool cleaning systems have been devised to ease the task of maintaining swimming pool surfaces free of settled debris. Some known systems utilize a plurality of "cleaning heads" disposed along bottom surfaces of swimming pools, wherein the cleaning heads have a large number of outlet openings disposed in a single plane so that successive jets of water are ejected along the bottom surfaces of a swimming pool to loosen settled debris from the bottom surface thereof. This enables the loosened debris to be easily advanced toward a drain located in the deepest portion of the swimming pool and drawn into a filter in the system which removes the debris from the water. A pool cleaning head of this type described is disclosed in U.S. Pat. No. 3,408,006, wherein the disclosed cleaning head includes a housing having two interspaced, staggered rings of saw-tooth-like camming surfaces or teeth disposed along an inner surface of a cylinder into which a piston or plunger having a pair of pins extending outwardly into the spaces between the teeth pop up and down as water pressure applied to the cleaning head is alternately cycled from zero pressure to a high pressure. Each time the water pressure is cycled, one of the pins engage a sloped upper or lower one of the camming surfaces and slides along that camming surface so that an outlet orifice in the upper end of the piston's vertical wall registers with a successive one of outlet openings, through which a jet of water is ejected.
However, the cleaning head disposed in U.S. Pat. No. 3,408,006 has several significant disadvantages, one being that the portion of the device in which the above-mentioned outlet openings are radially disposed always extends above the bottom surface of the pool, regardless of whether or not the cleaning head is being operated. Consequently, swimmers using the pool frequently stub their toes as they walk along the bottom surfaces of the swimming pool. Another disadvantage of the device of U.S. Pat. No. 3,408,006 is that a number of its features cause it to be unduly complex and expensive to manufacture.
Accordingly, it is an object of the invention to provide a cleaning head for installation along surfaces of a liquid container, such as a bottom surface of a swimming pool, wherein the cleaning head has an upper surface which is flush with the surface in which the cleaning head is installed if the cleaning head is not presently being operated.
It is another object of the invention to provide a pool cleaning head which avoids injury to the toes of swimmers.
Another disadvantage of the cleaning head described in U.S. Pat. No. 3,408,006 is that the structure of the outlet ports and the structure of the upper portion of the plunger and orifice in the plunger results in inefficient flow of water therethrough, producing turbulence which excessively limits the distance or extent of the jets of water ejected therefrom, thereby reducing the cleaning capability of the cleaning head. The high degree of turbulence of water moving through the upper portion of the plunger toward the elongated vertical orifice therein produces further turbulence in water as it approaches the orifice, preventing an efficient, narrow, high velocity jet of water from being formed and emitted from the orifice. The webs between the adjacent ports result in further frictional drag upon the emitted jet of water.
It is therefore another object of the invention to provide a pool cleaning head which more efficiently cleans the bottom of a swimming pool than the device described in U.S. Pat. No. 3,408,006 and is capable of cleaning a larger portion of the bottom of the swimming pool.
Another object of the invention is to provide a pool cleaning head having a more efficient "nozzling effect" upon ejected water than prior pool cleaning heads, enabling the cleaning head to produce more powerful jets of water which penetrate further along the bottom surface of the swimming pool than jets of water produced by prior pool cleaning heads.
Another disadvantage of the device of U.S. Pat. No. 3,408,006, relating to its complexity of structure, is the need to prevent a plunger retracting spring from "winding up" as the plunger rotates. Furthermore, the construction of the plunger is made more complex by the necessity of providing a large number of slots or holes in the lower portion thereof adjacent to the spring to prevent debris from collecting and interfering with the spring operation by allowing pressurized water to flow between the springs.
Another object of the invention is to provide a pool cleaning head which overcomes the foregoing shortcomings of the prior art.